Modern vehicles have bumper systems tuned for particular energy absorption during a vehicle-to-vehicle impact. However, tuning of bumper systems is not easy due to the many conflicting design requirements, such as limitations on the “package space” taken up by the bumper system, limitations on bumper beam flexure and rear intrusion into the space behind the beam, and limitations on cost, quality, dimensional consistency and consistency/predictability of the impact energy-absorbing profile during the impact stroke.
Recently, there has been increasing concern and consequently regulation addressing pedestrian impacts in an effort to reduce pedestrian injury during such an impact. Such regulation has added yet another level of difficulty and complexity to bumper system design and tuning of a bumper system.
Besides safety concerns, repair costs of the vehicle and meeting government/insurance test standards, there are also other important factors in the design of vehicle parts. In particular, vehicle parts which are designed to meet government test standards, known as low speed insurance tests, whereby they withstand low speed impact, i.e., at a speed of 4 to 15 kilometers per hour (km/h; 2.5 to 9 miles per hour (mph)).
There remains a need for vehicle energy absorbers to be made of a thermoplastic material that are easily manufactured, recover their original shape after a low speed impact, lead to cost savings for repairs and collision insurance and at the same time, meet government regulation standards for pedestrian protection.